Difference between revisions of "RTC"
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* From U-Boot there is a command '''date''' to read, reset, update the RTC. | * From U-Boot there is a command '''date''' to read, reset, update the RTC. | ||
| − | + | BIOS> '''help date''' for more information | |
| − | + | BIOS> '''date reset''' to be done after battery exchange to remove message '''### Warning: RTC oscillator has stopped''' | |
| − | + | BIOS> '''date 013122302007''' to set the date January 31th 2007 22h30. | |
| − | * From linux use the commande '''hwclock''' to read, write, synchronize the RTC | + | * From linux use the commande '''hwclock''' to read, write, synchronize the RTC: |
| − | + | # '''hwclock --help''' | |
| − | + | # '''hwclock -r''' to read hardware clock and print result | |
| − | + | # '''hwclock -s''' to set the system time from the hardware RTC clock | |
| − | + | # '''hwclock -w''' to set the hardware RTC clock to the current system time | |
| + | * and '''date''' to read and update system date and time while running: | ||
| + | # '''date --help''' for more information | ||
| + | # '''date -R''' to read hardware clock and print result | ||
| + | # '''date 013122302007''' to sets the system date january 31th 2007 22h30. | ||
| − | + | * Then, when booting you will see something like this: | |
| − | + | ||
| − | + | ||
| − | + | ||
| − | *Then, when booting you will see something like this: | + | |
ds1374 0-0068: setting the system clock to 2007-09-09 17:35:51 (1189359351) | ds1374 0-0068: setting the system clock to 2007-09-09 17:35:51 (1189359351) | ||
== Links == | == Links == | ||
* maxim-ic ds1374 datasheet http://datasheets.maxim-ic.com/en/ds/DS1374-DS1374U.pdf | * maxim-ic ds1374 datasheet http://datasheets.maxim-ic.com/en/ds/DS1374-DS1374U.pdf | ||
Revision as of 17:21, 27 July 2008
On this page, you will find usefull informations to use an external DS1374 Real Time Clock. This feature apply to the armadeus software release 2.0 and above.
Contents
[hide]Hardware
No permanent RTC is present on the APF9328 but it is not so complex to add a DS1374 (with integrated quartz) on the I2C bus. Do not forget to provide the two power-supply (VCC and Vbackup).
Configuration
First be sure to use an armadeus 2.0 or higher. The RTC/DS1374 support is already configured in U-BOOT and linux kernel 2.6.18.1 and higher. Therefore you have nothing to configure to use the RTC. Nevertheless these are the parameters to check to have the RTC supported:
$ make linux-menuconfig
- check the i2c module drivers "I2C support", "I2C DEVICE", "I2C HARDWARE/bus on imx"
- check the RTC module driver "RTC class", "set time from RTC" "RTC interface dev"
- if you integrates these module statically in the kernel then the system date will be set at power-up.
$ make
and reload your kernel and/or rootfs
Installation
- Installation is automatic with the default configuration but if you choose to compile rtc and i2c drivers as module then you have to load them:
$ modprobe i2c-imx $ modprobe rtc-ds1374 $ modprobe rtc-dev
- you will get something like this :
$ dmesg | grep rtc <6>ds1374 0-0068: rtc intf: sysfs <6>ds1374 0-0068: rtc intf: proc <6>ds1374 0-0068: rtc intf: dev (254:0) <6>ds1374 0-0068: rtc core: registered ds1374 as rtc0
Usage
- From U-Boot there is a command date to read, reset, update the RTC.
BIOS> help date for more information BIOS> date reset to be done after battery exchange to remove message ### Warning: RTC oscillator has stopped BIOS> date 013122302007 to set the date January 31th 2007 22h30.
- From linux use the commande hwclock to read, write, synchronize the RTC:
# hwclock --help # hwclock -r to read hardware clock and print result # hwclock -s to set the system time from the hardware RTC clock # hwclock -w to set the hardware RTC clock to the current system time
- and date to read and update system date and time while running:
# date --help for more information # date -R to read hardware clock and print result # date 013122302007 to sets the system date january 31th 2007 22h30.
- Then, when booting you will see something like this:
ds1374 0-0068: setting the system clock to 2007-09-09 17:35:51 (1189359351)
Links
- maxim-ic ds1374 datasheet http://datasheets.maxim-ic.com/en/ds/DS1374-DS1374U.pdf
